Thursday, May 17, 2012

Brake Tech: Stoptech Trophy BBK & Chasebays Booster Delete Kit

After months of chasing brake system demons and multiple on track failures, we finally seem to have solved all of the bugs and understand why the problems were occurring in the first place. Before I elaborate on how great the new setup is, I would like to take a moment and talk about the problems we were seeing that many of you may also see on similar applications. As you know our 2005 G35 is a completely built and turbo charged VQ35DE-Rev Up, and on these cars the brake booster uses vacuum from the engine to help braking efficiency in day to day driving. This booster uses driver input from the pedal and increasingly applies pressure to the caliper whether you change the brake input or not, almost like a pre abs system but with a tapered increase of pressure rather than a repetitive jab, like when abs kicks in. If you can imagine the pressure map of a stock setup it would look like a gradual curve over time with constant input. This same feature is the reason a stock brake progressively gets stiffer and harder to push with the more input you give, and also why on track they become very soft. 

Unfortunately with our turbocharged VQ, the vacuum being supplied to the brake booster was altered. This caused the Wilwood calipers to be non responsive and feel squishy or non existent, with zero braking force to the wheels while on track or under hard braking. I will note though that this problem was never noticeable on the street. Along with this problem the underpowered Wilwood calipers seemed to over heat almost constantly, destroying all types of pad compounds and cracking rotors left and right. Even when we added multiple cooling modifications to the brake system including NASCAR 4 inch Brake Ducts leading right to the caliper they still over heated. Another complaint about the Wilwoods are the inconsistent braking pressure applied through 3 differently tapered size pistons in the caliper itself. On top of all of these problems these rotors had a bad habit for knock back after long straights and it became very apparent the current setup was not going to work if we wanted the #144 G35 to be competitive. After testing everything we could, we finally had a solution.

Adressing our problems we did some testing and made a few phone calls and we got our hands on a Brake Boster Delete Kit thanks to ChaseBays and a brand new big brake kit from Stoptech! Stoptech knew of the high speeds and braking forces our time attack car would experience and they hooked us up with the first set of Trophy Series 6 Piston BBK on a G35, matched with 14inch AeroRotors. The deletion of the booster from the brake plumbing and addition of Stoptech's beautifully crafted light weight Trophy series brakes seem to have fixed everything. The huge calipers are lighter, bigger and dissipate heat easier, and brake pad changes are a cinch with its quick access design. Combine that with the multi piece AeroRotors, and knock back becomes very minimal and almost nonexistent. The pedal is now very very stiff and the length of input is much smaller and it leaves much less room to move the pedal. This is all due to the lack of the brake booster. It may be very stiff and hard to use, but the feel is much much more consistent. If the stock pressure graph looked like a curve then now with the modifications it would look like a straight line. There is no more assist from the car, but it still allows the use of ABS and other electronic functions like VDC and TSC. This provides the driver with complete control and allowing for a direct correlation between the drivers pedal input and the exact pressure sent to the calipers. Not only is it noticeable to me as the driver on track but we have also installed Computech Datamaxx brake pressure sensors and have watched the results in live data as the pressure is applied to the amount of braking force sent to the caliper. I would suggest the Chasebays delete kit to anyone who races there G or Z, but I would not suggest this for the average daily driven car because of the unbelievable stiffness of the pedal. But i would absolutely suggest Stoptech over any other brake brand on the market, one race day and I was sold for life. Be sure to get any of the products mentioned in this article through our online store or call us at the shop. And be sure to look for our next tech article on VDC Yaw Sensor Override vs. Engine Tuning. 

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